The invention relates to a method of and a device for drawing an optical fiber from a silica or doped silica preform.
In drawing an optical fiber from a solid preform, the preform is guided through a cylindrical furnace. The conical end of the preform, from which the fiber is drawn, is heated at a temperature above 2000.degree. C. The fiber is then guided through a device in which a thin layer of a synthetic resin is provided on the fiber, and is then guided through a furnace in which a solvent is removed from the synthetic resin and/or the layer of synthetic resin is polymerized.
It has been found that when the drawing speed is increased the attenuation of an optical fiber and the bandwidth can increase.
It is presumed that the increase in attenuation is the result of extra stresses which are present in a fiber and which are caused by volume relaxation and structure orientation. These stresses occur in particular if the temperature gradient traversed upon cooling the fiber in the temperature range from 1200.degree. to 1800.degree. C. is particularly large (larger than 500.degree. C. per sec.).